B-Chromosome Variability in Plants and Animals under Extreme Environments

Abstract

A review of data on B-chromosomes in populations of various systematic groups of plants and animals from their extreme habitats – the borders of the range and areas of the range exposed to unfavorable environmental factors is given. The analysis showed a rather similar picture of the distribution of B chromosomes in species from extreme habitats: there is a tendency to increase the number, occurrence and polymorphism of B chromosomes, which is accompanied by changes in the karyotype, genomic and chromosomal anomalies in their carriers. B chromosomes are often found in species with wide ranges. The possible adaptive role of B chromosomes in the vital activity of the organism and the evolution of genomes is discussed.